AVR-Chat

Hi, all...

i have implemented dtmf generator on 2313.
now i need to use other Port B pins as general IO.
i use the following code to read PORTB0 state and then write it back:

void modifyPortB (void)
{
	unsigned char temp, temp1;

	temp = PORTB;   
	temp1 = temp; 
	temp1 &= 0xfe;       
	temp = ~temp;
	temp &= 0x01; 
	PORTB = (temp1 | temp);
}

but with oscilloscope i observe a "glitch" on PWM signal.
Any suggestions?

TIA
-mirza-